“Digital image correlation (DIC) is a non-contact measurement method that have been increasingly used in many fields. The specimen surface is prepared with random speckles for motion tracking during the testing. A full-field displacement and strain data can be obtained by comparing the digital images taken before and after deformation.
Concrete is a non-homogeneous composite material with complex mechanical responses. DIC is a promising tool in structural testing as compared to conventional point-based instrumentation. With the development of DIC, full-field displacement data from material tests, such as uniaxial compressive test, can be used to experimentally characterize the mechanical behavior of concrete, which will contribute to the performance assessment of RC structures.
A three-dimensional (3D) DIC system has been successfully applied in several reinforced concrete (RC) structural experimental studies. Structural testing of a decommissioned reinforced concrete bent cap was conducted under distributed loading conditions, where DIC system was used to monitor the concrete strain. DIC can help identify crack pattern and estimate the crack width based on the displacement data at each side of cracks. DIC system was instrumented in a large-scale reinforced concrete column testing under cyclic lateral loading to investigate the rebar slip. Another application of DIC is to investigate the interface slip for a reinforced concrete slabs and beams with unreinforced concrete-to-concrete interface under bending.
By presenting those case studies, the advantages and limitations of DIC technique in the application of RC structural testing are discussed.
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